As a working vehicle shown in a side view in FIG. 15, a so-called skid-steer loader 100 is conventionally used. In such a skid-steer loader 100, a bucket 112, which can rise substantially vertically, is used to excavate, for example, earth, sand and the like, scoop them with the bucket 112 and load the earth and sand onto a truck not shown.
As the skid-steer loader 100 in which the bucket 112 can rise substantially vertical, the one that is disclosed in, for example, Japanese Patent Laid-open No. 6-26068 shown in FIG. 15 is cited. The right side is a front of a vehicle body in FIG. 15. The skid-steer loader 100 has a main frame 120 which extends longitudinally, has a link device 110 at the main frame 120, has an engine 122 at the rear part of the main frame 120, and has a driver's cab 130 on a top surface of the main frame 120. The main frame 120 has front wheels 141 at a lower front part thereof and rear wheels 142 at lower rear part thereof. A bucket 112 which is freely raised and lowered by a bucket cylinder 113 is rotatably provided at front end parts of a set of left and right lift arms 111 of the link device 110.
The link device 110 has the set of left and right lift arms 111, a set of left and right rear links 116, and a set of left and right rods 114. Rear end parts of the lift arms 111 are pivotably attached to upper end parts of the rear links 116, respectively. Lower end parts of the rear links 116 are pivotably attached at upper parts of a set of left and right upright members 121 that are provided at the rear part of the main frame 120. Mounting parts 111a each in a substantially inverted triangle shape are provided at central rear parts in a longitudinal direction of the lift arms 111 each with a bottom side part being fixed thereto. A vertex part of each of the mounting parts 111a extending downward is pivotably attached to each rear end part of the rod 114, and front end parts of the rods 114 are pivotably attached to an upper front part of the main frame 120. Rod upper end parts that are upper end parts of a set of left and right lift cylinders 115 are pivotably attached at rear parts of the bottom side parts of the mounting parts 111a. Cylinder lower end parts that are lower end parts of the lift cylinders 115 are pivotably attached in the vicinity of the engine 122 at the rear part of the main frame 120. Extension and contraction of the lift cylinders 115 make it possible to raise and lower tip ends of the lift arms 111 of the link device 110.
With the link device 110 of the skid steer loader 100 as described above, the front end parts of the lift arms 111 and the bucket 112 rise in such a manner as they move forward from the vehicle body following substantially an arc in the first half movement and they rise substantially vertically in the latter half of the movement when they rise as shown in FIG. 16.
As a skid-steer loader a bucket of which is made capable of rising substantially vertically of another prior art, there is the one disclosed in the U.S. Pat. No. 5,609,464 shown in FIG. 17. The right side is a front of a vehicle body in FIG. 17. A skid-steer loader 200 has a main frame 220 which extends longitudinally, has a link device 210 at the main frame 220, has an engine 222 at the rear part of the main frame 220, and has a driver's cab 230 on a top surface of the main frame 220. The main frame 220 has front wheels 241 at a lower front part thereof and rear wheels 242 at a lower rear part thereof. A bucket 212 which is freely raised and lowered by a bucket cylinder 213 is rotatably provided at front end parts of a set of left and right lift arms 211 of the link device 210.
The link device 210 has the set of left and right lift arms 211, a set of left and right rear links 216, and a set of left and right control links 214. Rear parts of the set of the lift arms 211 each has an end shape branched up and down, and each upper end part of the branched end is pivotably attached to an upper end part of each of the rear links 216. Lower end parts of the rear links 216 are pivotably attached at upper parts of upright members 221 that are provided at the rear part of the main frame 220. Lower end parts of the branched ends of the lift arms 211 are pivotably attached to the upper end parts of the control links 214, respectively. The lower end parts of the control links 214 are each pivotably attached in the vicinity of an engine 222 at a lower rear part of the main frame 220. Rod front end parts that are front end parts of a set of left and right lift cylinders 215 are each pivotably attached at central front parts in a longitudinal direction of the lift arms 211. Cylinder rear end parts that are rear end parts of the lift cylinders 215 are each pivotably attached in the vicinity of the engine 222 coaxially with the lower end parts of the control links 214, at the rear part of the main frame 220. Extension and contraction of the lift cylinders 215 make it possible to raise and lower tip ends of the lift arms 211 of the link device 210.
With the link device 210 of the skid-steer loader 200 as described above, the tip end parts of the lift arms 211 and the bucket 212 rise in such a manner as they move forward from the vehicle body following substantially an arc in the first half movement and they rise substantially vertically in the latter half of the movement, when they rise as shown in FIG. 18.
However, in the one shown in the aforementioned Japanese Patent Laid-open No. 6-26068, a lifting force of the front end parts of the lift arms 111 when the lift cylinders 115 are extended becomes as shown by the broken line in FIG. 19, and fluctuation of the lifting force is large. Accordingly, it becomes difficult to perform an excavating operation and a lifting operation with the bucket 112 which is provided at the front end parts of the lift arms 111. Since the rods 114 are located beside the driver's cab 130 when the lift arms 111 are raised as shown in FIG. 16, they obstruct an operator's view in a lateral direction, and the view in the lateral direction of the driver's cab is impaired. In a state in which the lift arms 111 are lowered as shown in FIG. 15, the lift cylinders 115 and the mounting parts 111a of the lift arms 111 are located beside the engine 122, which becomes an obstacle in performing maintenance of side faces of the engine 122, and a problem arises in maintainability.
In the one disclosed in the aforementioned U.S. Pat. No. 5,609,464 which is the other prior art, the rod parts of the front end parts of the lift cylinders 215 are each pivotably attached at the central front parts in the longitudinal direction of the lift arms 211, and therefore the lift cylinders 215 with a long stroke as shown in FIG. 18 are necessary. As shown in FIG. 18, when the lift arms 211 are raised, the lift cylinders 215 are located beside a driver's cab 230, which obstructs the operator's view in the lateral direction, and the lift cylinders 215 come in the view in the lateral direction, thus arising a problem in visibility. Further, in a state in which the lift arms 211 are lowered as shown in FIG. 17, the control links 214 and the lift cylinders 215 are located beside the engine 222, which becomes an obstacle in performing maintenance of the side faces of the engine 222, thus casing a problem in maintainability.